1. Field of the Invention
The present invention relates to a method of effecting high temperature vacuum heating and cooling suitable for conducting heat treatment such as baking to be performed on components used in a display apparatus or the like.
2. Related Background Art
Conventionally, apart from a liquid crystal display and a plasma display, an image display apparatus is available in which an electron beam is applied to a phosphor to display an image. The image display apparatus using an electron beam has a substrate face plate on which a phosphor is formed, a substrate rear plate on which there is formed, as an electron source for emitting an electron beam, a cold cathode device, such as a surface conduction type electron emission element, and an external frame for maintaining a reduced pressure atmosphere between the two substrates. In such an image display apparatus using an electron beam, an accelerated electron beam is applied from a surface conduction type electron emission element in a reduced pressure atmosphere to a phosphor, which is caused to emit light, thereby forming an image. In some of such devices, a thin plate-like spacer is provided between the substrates so that the two substrates may not be distorted when pressure reduction is effected in a space defined by the face plate, the rear plate, and the external frame.
The process for manufacturing such an image display apparatus using an electron beam involves heat treatments, which include the processing of firmly attaching the face plate and the rear plate to each other through the intermediation of the external frame, and a baking processing for removing from the substrate surfaces a chemical adsorption water in which water molecules are firmly bonded together through polarization. If an attempt is made to assemble the face plate and the rear plate under reduced pressure without performing this baking processing, a reduction in pressure is not easily achieved due to degassing attributable to chemical adsorption water, and it takes a rather long time to achieve the target vacuum degree for assembly.
When performing baking processing on a rear plate on which an electron source, wiring, etc. have been formed and on a face plate on which wiring and a phosphor have been formed, it is desirable for the processing time to be short from the viewpoint of mitigating the load of the heat treatment on the devices and wiring formed. Further, this baking processing is to be conducted a plurality of times in the production process, so that it is desirable for the time for each baking processing to be short from the viewpoint of reducing the requisite production time. Regarding the shortening of the requisite processing time of a baking processing to be performed on a component used in a vacuum processing apparatus, Japanese Patent Application Laid-open No. H6-124955 discloses a technique, according to which a reflector for heat reflection is provided around a workpiece (a component used in a vacuum processing apparatus) and heating means, and the temperature of a space surrounded by the reflector is raised to thereby effect a heating processing; when the workpiece is to be cooled, a cooling gas is circulated through a cooling jacket provided between the heating means and the reflector inside the vacuum chamber.
However, in the above prior-art technique, while consideration is given to a well-balanced cooling in a short time through a combination of natural cooling and a cooling gas flow, no measures are taken to effect both heating and cooling efficiently, and there has been a demand for an improvement in this regard. Further, in the above-described display apparatus, which has structures, such as a rear plate, a face plate, and a spacer, it is necessary to perform baking on each structure; however, performing baking on these structures individually results in an increase in processing time, which is undesirable. Further, in performing baking in a vacuum, heat distribution may be generated in the rear plate, face plate, spacer, etc., depending on their configuration, which means there is a danger of distortion or cracking being generated in these components.